Conventionally, yarn winding methods applied to spindle drive type apparatuses are roughly classified into two types as follows.
1. A method wherein the wind ratio is kept constant so that the number of yarn wraps on the take-up package during one complete cycle of the traverse, i.e., one full stroke in each direction, is constant during the winding operation. PA0 2 A method wherein the angle of wind is kept constant during the winding operation. PA0 means for adjusting the wind ratio connected to the traverse device or the spindle; PA0 a first synchronous motor connected to the traverse device and driving the traverse device; PA0 a second synchronous motor connected to the spindle and driving the spindle; and PA0 a frequency variable power source means capable of connecting to both the first and second motors. PA0 (1) Since a power source simultaneously drives a spindle and a traverse device in the present invention, no electrical means is necessary by which the frequencies of two kinds of electric powers are proportionally controlled. Accordingly, the cost of the yarn winding apparatus of the present invention is low. PA0 (2) The construction of the yarn winding apparatus of the present invention is simple, and the maintenance of the apparatus is easy, since it is unnecessary to connect the spindle and the traverse device to each other by means of a mechanical transmission member, such as a timing belt. PA0 (3) The wind ratio can always be precisely constant since a single frequency variable power source drives both a spindle and a traverse device.
The present invention relates to an improvement of a yarn winding apparatus for performing the method 1 described above. Yarn winding apparatus for winding yarn at a constant wind ratio is well known, for example, from the disclosure of Japanese patent application Laid-open No. 93138/79 wherein tension in running yarn is controlled at a predetermined constant value by utilizing a tension meter to detect the tension or peripheral speed of a yarn package formed on a bobbin. The tension is controlled at a predetermined value by varying the speed of a contact roller or the like which is rotating in contact with the peripheral surface of the wound package.
Incidentally, in conventional yarn winding apparatuses of constant wind ratio type the following methods A and B have been utilized in order to maintain the wind ratio at a certain constant value.
A. The spindle and the traverse device are mechanically and operably connected to each other and are driven by means of a single motor so that the wind ratio is mechanically maintained at a constant value.
B. The spindle and the traverse device are connected to independent synchronous driving motors, respectively, and the synchronous motors are connected to a power source for driving the spindle and a power source for driving the traverse device, respectively. The spindle driving power source generates electric power of predetermined frequency, and the traverse driving power source generates electric power of frequency being proportional to the frequency of the spindle driving power source so that the yarn can be wound onto a bobbin at a constant wind ratio.
However, the construction of the conventional yarn winding apparatuses wherein method A described above takes place is very complicated, since the spindle and the traverse device are connected to each other by means of a mechanical transmission member, such as a timing belt. Accordingly, maintenance of such apparatuses is not easy.
Contrary to this, according to the conventional yarn winding apparatuses wherein method B described above takes place can overcome the above-described defects inherent to the conventional apparatuses. However, the frequency ratio between the power sources must precisely be controlled throughout the winding operation. In this case, the dynamic characteristics of the power sources must be high, since the frequencies of the power sources must always be proportional to each other. Accordingly, the prices of the frequency variable power sources are high, and the construction cost of the winding apparatus becomes high.